Boston’s Big Dig—the most expensive transportation project in American history—is proving to be a boon to lawyers as well as construction companies. The $14.6 billion "Central Artery and Third Harbor Tunnel" project, which buries Interstate 93 beneath downtown Boston and connects the Massachusetts Turnpike to Logan Airport, has been plagued by cost overruns, leaks and other problems.

So far, the state’s Turnpike Authority has filed 11 lawsuits against Big Dig contractors and designers for things like misjudging the length of a tunnel and forgetting to leave room for a gas main. Ten of the suits are relatively small potatoes, totaling about $13.9 million, according to a review by the Associated Press.

The big one, though, is a breach of contract action against the project manager, Bechtel/Parsons Brinckerhoff, which earned $140 million in profits and another $6 million in fees on the contract, about one percent of the total price. The authority claims that Bechtel low-balled the project price when it knew, or should have known, that it would actually cost billions more than its estimate.